I also have the AA cat back and X-pipe, but I had the cats installed about 3 weeks after the initial system. The smell was killing my wife I have to agree though, The sound is amazing. I drive the car more now just to hear that sound. Its amazing how many folks in other high performance vehicles turn to look at the car when they hear me drive by. I really dig the backfiring noise as well....... Overall great system and the car is much more responsive in the mid range. The stock system was WAY TOO muted.